Biomedical subjects

H Chung

Publications and source records attributed to H Chung.

At least 37 records · Page 2Linked to original sources

PubMed2001

Mechanism of growth inhibitory effect of Mitomycin-C on cultured human retinal pigment epithelial cells: apoptosis and cell cycle arrest.

PURPOSE: To investigate the therapeutic potential of Mitomycin-C (MMC) in the management of proliferative vitreoretinopathy, the antiproliferative effect of MMC on cultured human retinal pigment epithelial (RPE) cells were investigated in vitro. METHODS: Drug sensitivities of cultured human RPE cells to MMC were determined using the tetrazolium dye assay. In order to detect the presence of apoptosis, DNA fragmentation was assessed by DAPI staining, and TdT-dUTP nick-end labeling (TUNEL) assay. The relative amount of DNA fragmentation was quantified by flow cytometric analysis. To analyze the cell cycle response of RPE cells to MMC, flow cytometric analysis of propidium iodide stained nuclei was performed. The levels of proteins related to DNA damage in the RPE cells were then determined by Western blot analysis. RESULTS: MMC inhibited cell proliferation in a dose-dependent manner. The majority of RPE cells following treatment with 10 microg/ml of MMC exhibited fragmented nuclei as observed by DAPI staining and TUNEL assay. Cell cycle analysis demonstrated an accumulation of cells arrested in S and G2/M phase following treatment with 1 microg/ml of MMC. At 10 microg/ml of MMC, a dramatic increase of the cell population in the sub G1 peak, which can be considered a marker of cell death by apoptosis, was observed by flow cytometry. Western blot analysis of p53 and p21 revealed a gradual increase in the level of these proteins when RPE cells were exposed to increasing concentrations of MMC. CONCLUSIONS: This study demonstrated that the response of RPE cells to MMC was bi-directional: 1) partial arrest of the cell cycle at S, G2/M phase, and 2) induction of apoptotic cell death.

Adolescent↗

PubMed2001

The clinical and ocular manifestations of Takayasu arteritis.

PURPOSE: To evaluate the clinical and ocular manifestations of Takayasu arteritis and the fundus fluorescein angiography (FFA) characteristics of Takayasu retinopathy (TR). PATIENTS AND METHODS: Medical records and fundus fluorescein angiograms of 156 eyes of 78 patients with Takayasu arteritis were reviewed. Fundus FA using a wide-field fundus camera (60 degrees) was performed in 19 patients, and conventional angiography or spiral computed tomographic angiography was performed in all 78 patients. RESULTS: The series included 67 female and 11 male patients; mean age at time of diagnosis was 26.7 years (range, 4-61 years). Hypertension was found in 44 (56.4%) patients, ischemic cerebrovascular symptoms in 18 (23.1%) patients, and amaurosis fugax in 20 (25.6%) patients. On fundus examination, no retinopathy was found in 87 (55.8%) eyes; hypertensive retinopathy was found in 48 (30.8%) eyes; and TR was found in 21 (13.5%) eyes. Patients with TR had carotid artery or aortic arch involvement, and patients with hypertensive retinopathy had involvement of the descending aorta or renal artery and sparing of the carotids. Best-corrected visual acuity in TR Stage 1 to 3 ranged from 20/15 to 20/30, but in Stage 4, it ranged from 20/200 to hand motions because of secondary ocular complications. On FFA, the arm-to-retina circulation time was prolonged in all 21 eyes with TR (mean, 22.7+/-8.9 seconds), but only 14 eyes showed delayed arteriovenous filling time, which was mainly found in chronic, moderate to severe TR, Stage 3 or 4. Arteriovenous anastomosis was found in all 12 eyes with Stage 3 and 4 TR. CONCLUSIONS: Delayed arm-to-retina circulation time is shown in all cases of TR, but delayed arteriovenous filling time is mostly found in moderate and severe TR. During ophthalmic examination, the delay of arteriovenous filling time and formation of arteriovenous anastomosis must be examined carefully to prevent visual deterioration.

Adolescent↗

PubMed2001

Exposure of workers to airborne microorganisms in open-air swine houses.

This study quantified the levels of airborne microorganisms in six swine farms with more than 10,000 pigs in subtropical Taiwan. We evaluated breeding, growing, and finishing stalls, which were primarily open-air buildings, as well as partially enclosed farrowing and nursery piggeries. Airborne culturable bacteria, gram-negative bacteria, and fungi were placed on appropriate media by using an all-glass impinger or single-stage Andersen microbial sampler. Results showed that mean concentrations of culturable bacteria and gram-negative bacteria were 3.3 x 10(5) and 143.7 CFU/m(3), respectively. The concentration of airborne culturable fungi was about 10(3) CFU/m(3), with Cladosporium the predominant genus. The highest airborne levels of culturable bacteria and gram-negative bacteria were identified in the finishing units. The air of the nursery stalls was the least contaminated with culturable and gram-negative bacteria. Irregular and infrequent cleaning, high pig density, no separation of wastes from pen floors, and accumulation of water as a result of the processes for cleaning and reducing pig temperature possibly compromise the benefits of the open characteristic of the finishing units with respect to airborne bacterial concentration.

Air Microbiology↗

PubMed2001

Srg3, a mouse homolog of yeast SWI3, is essential for early embryogenesis and involved in brain development.

Srg3 (SWI3-related gene product) is a mouse homolog of yeast SWI3, Drosophila melanogaster MOIRA (also named MOR/BAP155), and human BAF155 and is known as a core subunit of SWI/SNF complex. This complex is involved in the chromatin remodeling required for the regulation of transcriptional processes associated with development, cellular differentiation, and proliferation. We generated mice with a null mutation in the Srg3 locus to examine its function in vivo. Homozygous mutants develop in the early implantation stage but undergo rapid degeneration thereafter. An in vitro outgrowth study revealed that mutant blastocysts hatch, adhere, and form a layer of trophoblast giant cells, but the inner cell mass degenerates after prolonged culture. Interestingly, about 20% of heterozygous mutant embryos display defects in brain development with abnormal organization of the brain, a condition known as exencephaly. Histological examination suggests that exencephaly is caused by the failure in neural fold elevation, resulting in severe brain malformation. Our findings demonstrate that Srg3 is essential for early embryogenesis and plays an important role in the brain development of mice.

Animals↗

PubMed2001

Evaluation of posttreatment response of hepatocellular carcinoma with contrast-enhanced coded phase-inversion harmonic US: comparison with dynamic CT.

PURPOSE: To assess the reliability of contrast material-enhanced real-time gray-scale ultrasonography (US) in evaluating posttreatment response of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty HCC nodules were examined with contrast-enhanced coded phase-inversion harmonic US before and after treatment. Intratumoral vascularity was assessed with continuous imaging in the early arterial phase and with interval-delay scanning to depict tumor parenchymal flow during the blood pool phase. Vascular findings at US were compared with those at dynamic computed tomography (CT). RESULTS: In 50 HCC nodules before treatment, positive enhancement of tumor vessels and tumor parenchymal flow (stain) were observed in 47 (94%) and 46 (92%), respectively. Either tumor vessel or stain was visualized with coded harmonic US in 49 of 50 nodules. Eighty-one coded harmonic US studies were performed in 49 posttreatment HCC nodules. Compared with dynamic CT, the sensitivity, specificity, and accuracy of coded harmonic US in helping to detect positive enhancement in pretreatment HCC were 98% (49 of 50), 100% (50 of 50), and 98% (49 of 50), respectively. After treatment, positive enhancement of tumor vascularity was observed in 39 (48%) of 81 posttreatment studies, and no enhancement was observed in others (52%). Coded harmonic US demonstrated partial and no enhancement of tumor vascularity in four and one nodule, respectively; after transcatheter arterial embolization with iodized oil, evaluation of tumor vascularity with dynamic CT was difficult because of the presence of oil. CONCLUSION: With enhancement, coded harmonic US depicted tumor vascularity by showing tumor vessels in a real-time fashion at continuous imaging and tumor parenchymal flow at interval-delay scanning.

Adult↗

PubMed2001

Effect of the absence of heat shock protein 70.1 (hsp70.1) on retinal photoreceptors in normal and rd mice.

The purposes of this study are to elucidate the retinal changes of heat shock protein 70.1 (hsp70.1) knockout mice and to compare them between in normal and in retinal degeneration (rd) mice. Eyes of hsp70.1 wild type (+/+) and knockout (-/-) mice in the C57BL/6 or FVB genetic backgrounds respectively, which were reared in the normal environment, were examined by fundus photography, electroretinography, light microscopy, terminal dUTP nick-end labeling (TUNEL) stain, and immunohistochemistry. In C57BL/6 mice, fundus photography showed no changes between hsp70.1+/+ and -/- mice at 1 and 6 months of age. Electroretinographic examination showed a tendency of decreased amplitude of a- and b-wave with aging in both genotype, but there were not different statistically. The ratios of the thickness of inner nuclear and outer nuclear layer to the retinal thickness were respectively decreased with aging in both genotype, but there were not different statstically. TUNEL assay showed a few positively labeled cells in the ganglion cell, inner nuclear and outer nuclear layers and the immunohistochemistry showed no immunopositivity of hsp70 in the inner segments of photoreceptor cell layer in both genotype. In rd mice, fundus photography showed a narrowing of the retinal vessels at the age of 4 weeks, however, there were no differences of retinal changes including pigment epithelial layer in both genotype. Electroretinographic examination at the postnatal 2, 3 and 4 weeks showed no differences between them. Loss of photoreceptor cell and outer nuclear layers showed no differences in both genotype. In conclusion, there were no differences of the retinal changes at least under the normal environmental condition in hsp70.1+/+ and -/- mice. These results show that hsp70.1-/- mice can be used to study the role of hsp70.1 to the external stress to the retina.

Animals↗

PubMed2001

Extraocular muscle changes after cryotherapy for retinopathy of prematurity and the development of strabismus in premature infants.

To find out whether the cryotherapy for the treatment of the retinopathy of prematurity (ROP) causes structural changes of the extraocular muscle (EOM), and also whether the changes are related with the occurrence of strabismus. To examine the acute stage change, we conducted a transconjunctival cryotherapy around the superior rectus muscle of a rabbit and resected it 0, 3, 7, 14, and 28 days after the cryotherapy. In observing chronic changes, we first categorized patients who had an esotropia surgery into groups, one of which combined prematurity and cryotherapy and one group affected by prematurity but without having had cryotherapy. Then we compared the change of EOM with that of a fullterm infant group. In a rabbit, edema, acute inflammatory cells and a large amount of degenerated muscle fibers were observed immediately after the cryotherapy and on the 3rd day. On the 7th day, regenerated muscle fibers were observed and on the 14th day, the inflammatory cells decreased and the amount of regenerated muscle fiber increased. On the 28th day, abnormal findings were not observed any more and the muscle was found to be normal. When chronic changes of EOM in human on 1 1/2 to 8 1/2 years after cryotherapy, there were no abnormal findings observed in three groups. From the study, we can infer that cryotherapy can cause acute inflammation and necrosis of muscle fiber but such an acute change will improve and does not result in structural change in the long term. Therefore, the occurrence of strabismus in patients with ROP is considered to be attributable to reasons other than injury of EOM.

Animals↗

PubMed2001

Deflazacort increases osteoclast formation in mouse bone marrow culture and the ratio of RANKL/OPG mRNA expression in marrow stromal cells.

Information on precise effects of deflazacort on bone cell function, especially osteoclasts, is quite limited. Therefore, the present study was undertaken to test effects of deflazacort on osteoclast-like cell formation in mouse bone marrow cultures and on the regulation of osteoprotegerin (OPG) and its ligand (RANKL) mRNA expressions by RT-PCR in the ST2 marrow stromal cells. TRAP-positive mononuclear cells increased after the treatment of deflazacort at 10(-9) to 10(-7) M alone for 6 days in a dose-dependent manner. Number of TRAP-positive multi-nucleated cells (MNCs) increased significantly with combined treatment of deflazacort at 10(-7) M and 1,25-(OH)2D3 at 10(-9) M compared to that of cultures treated with 1,25-(OH)2D3 alone (p<0.05). Exposure to deflazacort at 10(-7) M in the presence of 1,25-(OH)2D3 at 10(-9) M in the last 3-day culture had greater stimulatory effect on osteoclast-like cell formation than that of the first 3-day culture did. Deflazacort at 10(-10) -10(-6) M downregulated OPG and upregulated RANKL in mRNA levels in a dose-dependent manner. These observations suggest that deflazacort stimulate osteoclast precursor in the absence of 1,25-(OH)2D3 and enhance differentiation of osteoclasts in the presence of 1,25-(OH)2D3. These effects are, in part, thought to be mediated by the regulation of the expression of OPG and RANKL mRNA in marrow stromal cells.

Animals↗

PubMed2001

The value of cystoscopy and intravenous urography after magnetic resonance imaging or computed tomography in the staging of cervical carcinoma.

The clinical staging system for cervical carcinoma presently recommended by the International Federation of Gynecology and Obstetrics (FIGO) does not include MRI or CT findings and thus suffers limited accuracy. Recently however, the positive contributions of MRI and CT to preoperative staging have been reported. This study involves a determination of the value of routine cystoscopy and intravenous urography, in the detection of bladder invasion or hydronephrosis resulting from cervical carcinoma, among patients who had undergone MRI or CT. Among a total 296 patients with cervical carcinoma, 271 patients (92%) had undergone MRI and 25 (8%) CT. Bladder invasion was identified pathologically by cystoscopic biopsy in 8 (57%) of the 14 patients with suspected bladder invasion on MRI or CT. There was no bladder invasion in any of the other cases lacking in bladder invasion evidence on MRI or CT. Hydronephrosis was identified by intravenous urography in 18 patients, as it also was in all of these cases on MRI or CT, confirming a negative predictive value for MRI or CT, in detecting bladder invasion or hydronephrosis from cervical carcinoma, of 100%. Therefore, although MRI or CT cannot totally replace cystoscopy, the latter is unnecessary in the absence of bladder invasion evidence on MRI or CT. Intravenous urography, however, can be safely omitted whenever MRI or CT is performed.

Adult↗

PubMed2001

Photodetector sensitivity level and heidelberg retina flowmeter measurements in humans.

PURPOSE: In vitro models suggest that Heidelberg retina flowmeter (HRF) measurements are affected by changes in photodetector sensitivity. We measured blood flow in a single volume of human retinal tissue in vivo at various sensitivity (DC) levels. METHODS: The peripapillary retinal regions of 12 normal subjects were examined by HRF under five different sensitivity settings: (1) average DC range below 100; (2) average DC range below 125; (3) average DC range near 150 (normal sensitivity); (4) average DC range above 175; and (5) average DC range above 200 or extremely overexposed. The distributions of flow values were examined by pointwise analysis. All pixels from a common tissue location were analyzed, and the effect of their brightness on the flow measurement was evaluated by ANOVA with Fisher's protected least significant difference model. RESULTS: ANOVA analysis of image DC level showed that significantly different DC levels were achieved for each of the five sensitivity settings (P < 0.0001). Flow values decreased with increasing DC for each of the 25th percentile, 50th percentile (P: < 0.0001 for each), 75th percentile (P: = 0.0026), 90th percentile (P: = 0.0216), and mean (P: = 0.0004) flow values. The percentage of pixels with values of zero (avascular tissue) increased with increasing photodetector sensitivity (P< 0.0001). CONCLUSIONS: Improper sensitivity settings alter the detected percentage of avascular tissue and the blood flow measurements in tissue containing capillaries. Consistent assessment of retinal blood flow requires consistent photodetector sensitivity settings between longitudinal images.

Adult↗

PubMed2001

Exposure assessment to airborne endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide in open style swine houses.

Information is limited for the exposure levels of airborne hazardous substances in swine feed buildings that are not completely enclosed. Open-style breeding, growing and finishing swine houses in six farms in subtropical Taiwan were studied for the airborne concentrations of endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide. The air in the farrowing and nursery stalls as partially enclosed was also simultaneously evaluated. Three selected gases and airborne dusts were quantified respectively by using Drager diffusion tubes and a filter-weighing method. Endotoxin was analyzed by the Limulus amoebocyte lysate assay. Average concentration of airborne total endotoxin among piggeries was between 36.8 and 298 EU/m(3), while that for respirable endotoxin was 14.1-129 EU/m(3). Mean concentration of total dust was between 0.15 and 0.34 mg/m(3), with average level of respirable dust of 0.14 mg/m(3). The respective concentrations of NH3, CO2 and H2S were less than 5 ppm, 600-895 ppm and less than 0.2 ppm. Airborne concentrations of total dust and endotoxin in the nursery house were higher than in the other types of swine houses. The finishing house presented the highest exposure risk to NH3, CO2 and H2S. Employees working in the finishing stalls were also exposed to the highest airborne levels of respirable endotoxin and dust. On the other hand, the air of the breeding units was the least contaminated in terms of airborne endotoxin, dust, NH3, CO2 and H2S. The airborne concentrations of substances measured in the present study were all lower than most of published studies conducted in mainly enclosed swine buildings. Distinct characteristics, including maintaining swine houses in an open status and frequent spraying water inside the stalls, significantly reduce accumulation of gases and airborne particulates.

Air Pollution, Indoor↗

PubMed2001

Tissue slices revisited: evaluation and development of a short-term incubation for integrated drug metabolism.

This work details the development of a model for the rapid evaluation of drug metabolism in an integrated fashion using in situ architecture of the liver. A Krumdieck tissue slicer was used to generate slices from 10-mm cores of rat liver (approximately 250-microm thick). Initial unsuccessful efforts with 6-well plate-based incubation were overcome with the use of a dynamic (rotating) incubation in 23-ml liquid scintillation vials containing titanium mesh supports for the slice. Incubation of 1 slice/5 ml of a Krebs-Henseleit solution buffered with HEPES showed a <2% increase over the initial 25% release of lactate dehydrogenase over 2 h of incubation at 37 degrees C under ambient oxygen conditions. Coupled O-dealkylase and conjugative metabolism of alkoxycoumarin derivatives was shown to be linear for both 7-methoxy- and 7-ethoxycoumarin (100 microM) with a low amount of nonconjugated 7-hydroxycoumarin (7-HC) at all time points. Metabolic profiles for 7-methoxy- and 7-ethoxycoumarin were compared between slice and microsomal incubations generated from the same tissue. The use of 7-HC as a primary substrate not only provided an assessment of the capacity-based differences in oxidative versus conjugative metabolism but also capacity-based differences in glucuronidation and sulfation. These studies underscore the physiological fact that phase I metabolism has a lower capacity for substrate metabolism than phase II metabolism. Additionally, this technique provides a model for examination of pharmacodynamic and pharmacokinetic influences in the context of maintenance of the in situ architecture of the liver.

Animals↗

PubMed2000

Regulation of beta 1 integrin-mediated adhesion by T cell receptor signaling involves ZAP-70 but differs from signaling events that regulate transcriptional activity.

Stimulation of the CD3/TCR results within minutes in an increase in T cell adhesion mediated by beta(1) integrins. The biochemical pathways that control CD3-mediated increases in beta(1) integrin-mediated adhesion remain poorly characterized. In this study, the role of the tyrosine kinase ZAP-70 in the regulation of beta(1) integrin activity by the CD3/TCR was investigated. CD3 stimulation did not increase beta(1) integrin-mediated adhesion of the ZAP-70-deficient Jurkat T cell line, P116, to the beta(1) integrin ligand fibronectin. Reintroduction of wild-type ZAP-70, but not a kinase-inactive variant, K369R, corrected the adhesive defect observed in P116 T cells. In addition, the kinase-inactive ZAP-70 mutant inhibited CD3-induced adhesion of primary human T cell blasts. Interestingly, a ZAP-70 mutant with a tyrosine to phenylalanine substitution at position 319 (Y319F) restored the adhesive defect in P116 T cells, even though Y319F ZAP-70 failed to fully reconstitute CD3-initiated NF-AT-dependent transcription and tyrosine phosphorylation of the LAT adapter protein. Finally, expression of mutants of LAT and the SLP-76 adapter protein that modulate CD3-mediated activation of an NF-AT reporter gene failed to block CD3-induced increases in beta(1) integrin-mediated adhesion. These observations support a model in which the tyrosine kinase activity of ZAP-70 kinase is critical for regulation of beta(1) integrin activity by CD3/TCR. However, the signaling events downstream of ZAP-70 that regulate CD3/TCR-mediated activation of beta(1) integrin function exhibit key differences when compared with the signaling pathways that regulate transcriptional events initiated by CD3/TCR stimulation.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Macrophage inflammatory protein 1-alpha is a potential osteoclast stimulatory factor in multiple myeloma.

This study was designed to determine if macrophage inhibitory protein-1 alpha (MIP-1 alpha), a recently described osteoclast (OCL) stimulatory factor,(1) was present in marrow from patients with multiple myeloma (MM) and possibly involved in the bone destructive process. MIP-1 alpha, but not interleukin-1 beta (IL-1 beta), tumor necrosis factor-beta (TNF-beta), or interleukin-6 (IL-6), messenger RNA was elevated in freshly isolated bone marrow from 3 of 4 patients with MM compared to normal controls. Furthermore, enzyme-linked immunosorbent assays of freshly isolated bone marrow plasma detected increased concentrations of hMIP-1 alpha (range, 75-7784 pg/mL) in 8 of 13 patients (62%) with active myeloma, in 3 of 18 patients (17%) with stable myeloma (range, 75-190.3), as well as in conditioned media from 4 of 5 lymphoblastoid cell lines (LCLs) derived from patients with MM. Mildly elevated levels of MIP-1 alpha were detected in 3 of 14 patients (21%) with other hematologic diagnoses (range, 80.2-118.3, median value of 96 pg/mL) but not in normal controls (0 of 7). MIP-1 alpha was not detected in the peripheral blood of any patients with MM. In addition, recombinant hMIP-1 alpha induced OCL formation in human bone marrow cultures. Importantly, addition of a neutralizing antibody to MIP-1 alpha to human bone marrow cultures treated with freshly isolated marrow plasma from patients with MM blocked the increased OCL formation induced by these marrow samples but had no effect on control levels of OCL formation. Thus, high levels of MIP-1 alpha are expressed in marrow samples from patients with MM, but not in marrow from patients with other hematologic disorders or controls, and support an important role for MIP-1 alpha as one of the major factors responsible for the increased OCL stimulatory activity in patients with active MM. (Blood. 2000;96:671-675)

Bone Marrow↗

PubMed2000

Effects of incorporation of immunoglobulin G and complement component C1q on uptake and degradation of Alzheimer's disease amyloid fibrils by microglia.

Microglia are macrophage-like immune system cells found in the brain. They are associated with Alzheimer's Disease plaques, which contain fibrillar beta-amyloid (fAbeta) and other components such as complement proteins. We have shown previously that murine microglia bind and internalize fAbeta microaggregates via the type A scavenger receptor, but degradation of internalized fAbeta is significantly slower than normal degradation. In this study, we compared internalization by microglia of fAbeta microaggregates to that of anti-Abeta-antibody-coated fAbeta (IgG-fAbeta) microaggregates and found that the uptake of the latter is increased by about 1.5-fold versus unmodified fAbeta. The endocytic trafficking of IgG-fAbeta is similar to that of fAbeta microaggregates, following an endosomal/lysosomal pathway. We also compared the internalization of fAbeta microaggregates to that of complement protein, C1q-coated fAbeta microaggregates, and found that the levels of uptake are also increased by about 1.5-fold. Rates of degradation of both types of modified fAbeta microaggregates are unchanged compared with unmodified fAbeta microaggregates. We demonstrated by blocking studies that internalization of IgG-fAbeta is mediated by Fc receptors. These data suggest that, in vivo, several different microglial receptors may play a part in internalizing fAbeta, but the involvement of other receptors may not increase the degradation of fAbeta.

Alzheimer Disease↗

PubMed2000

In vivo gene transfer to the mouse nasal cavity mucosa using a stable cationic lipid emulsion.

We evaluate a new cationic emulsion as a mucosal gene carrier and elucidate the relationship between the transfection efficiency and the stability of the carrier/DNA complex. A cationic lipid emulsion was formulated with soybean oil and 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as major components and was used to transfer genes to the epithelial cells of the mouse nasal cavity via intranasal instillation. Correlation between the transfection efficiency and the stability of the carrier/DNA complex was investigated by measuring the carrier size changes and by observing the degree of DNA protection against DNase I digestion in the presence of heparin. The cationic emulsion showed at least 3 times better transfection activity than the liposomal carriers in nasal mucosae. The cationic emulsion was stable in the presence of heparin whereas the liposomal carriers became very unstable. Unlike DNA in liposome/DNA complexes, DNA in the emulsion/DNA complex was resistant to heparin exchange and DNase I digestion. The cationic emulsion was more effective in delivering DNA to nasal mucosae than commercially available liposomal carriers. The transfection activities of the lipid carriers in nasal cavity mucosae are in agreement with the stability of the lipid carriers and their complexes with DNA.

Animals↗

PubMed2000

Production and molar yield of 2-phenylethanol by Pichia fermentans L-5 as affected by some medium components.

In this study, the effects of carbon sources and various levels of sucrose (0-30%) yeast extract (0-1.25%) and phenylalanine (0-0.2%) on the production of 2-phenylethanol by Pichia fermentans L-5 were investigated. Results revealed that among the 11 carbon sources tested, glycerol and sucrose were suitable carbon sources for P. fermentans L-5 resulting in production of higher amounts of 2-phenylethanol. In the medium that contained 18% sucrose, P. fermentans L-5 produced the highest amount of 2-phenylethanol, 283.4 mg/l with a molar yield of 0.77, was noted among the various levels of sucrose tested. Increasing the amount of phenylalanine added to the culture medium to 1.0% resulted in increased production of phenylethanol. Enhanced production of 2-phenylethanol, 453.1 mg/l by P. fermentans L-5 with a molar yield of 0.71 for phenylethanol was obtained in the medium containing 18% sucrose, 0.25% yeast extract and 0.1% phenylalanine after 16 h of fermentation.

Journal Article↗

PubMed2000

A cationic lipid emulsion/DNA complex as a physically stable and serum-resistant gene delivery system.

PURPOSE: To develop a non-viral gene delivery system in the form of an oil-in-water (o/w) lipid emulsion. METHOD: Cationic lipid emulsions were formulated with soybean oil, 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as a cationic emulsifier and other co-emulsifiers. The physical characteristics of the lipid emulsion and the emulsion/DNA complex were determined. The in vitro transfection efficiency of the emulsion/DNA complex was determined in the presence of up to 90% serum. RESULTS: The average droplet size and zeta potential of emulsions were ca. 180 nm and ca. +50 mV, respectively. Among the emulsions, a stable formulation was selected to form a complex with a plasmid DNA encoding chloramphenicol acetyltransferase. By increasing the ratio of emulsion to DNA. zeta-potential of the emulsion/DNA complex increased monotonously from negative to positive without any changes in the complex size. The complex was stable against DNase I digestion and an anionic poly-L-aspartic acid (PLAA). The complex delivered DNA into the cells successfully, and the transfection efficiency was not affected by complex formation time from 20 min to 2 h. More importantly, the cationic lipid emulsion facilitated the transfer of DNA in the presence of up to 90% serum. CONCLUSIONS: The cationic lipid emulsion/DNA complex has physical stability and serum resistant properties for gene transfer.

Animals↗